The present invention relates generally to modular stairways. More particularly, it is a novel modular stairway in which the primary structural support for the stairway is provided by a stringer or stringers formed with a relatively planar flat top. The stringers may be conventional lumber, such as a two-by-six, or it may be made of engineered lumber such as linear veneer lumber (LVL), and the steps, railing, and other details of the stairway are defined by various pre-fabricated modules and components that interfit with such a simple stringer to form a surprisingly strong, unified, visually pleasing stairway. The devices and methods of the present invention may be applied to stairways of single straight flights or multiple flights with virtually any shape of landings between, and to both open staircases where the balustrade is mounted on the treads and closed staircases where balustrades, if used, are mounted on a rake wall adjacent to the treads.
In a conventional stairway, stringers are cut one at a time from oversized dimensional lumber, such as a conventional two-by-twelve, with notches cut so that the effective structural support of the lumber is approximately fifty-percent of its original thickness, equivalent to a two-by-six. The notches that are cut out of the two-by-twelve receive risers and treads for the stairway and the portions removed are discarded, wasting much lumber. They are difficult to cut consistently, leading to the development and use of numerous tools to mark and cut the stringer. Conventional stringers are difficult to erect and anchor on site in a way that maintains the required parallel and level relationship to each other, perpendicular relationship to the floor, and perpendicular relationship to the header to which they are attached.
Conventional stairway construction also involves substantial problems in the on-site fitting of individual tread and riser boards. Tread and riser boards are individually measured, cut to fit against and between the imprecise and irregular notches in the stringers, and anchored using fasteners that reduce the load-bearing capacity of the stringers. Furthermore, on-site attachment of balustrade, carpet, aesthetic fascia, and trim are time-consuming processes involving for each piece laborious measuring, cutting, and anchoring.
Others have recognized the drawbacks of conventional stairways, including the notched stringers often used, and have attempted to overcome these drawbacks by creating brackets and other devices for use in building stairways. For example, various stairway-related devices are disclosed in U.S. Pat. Nos. 4,464,870, 4,850,164, 4,875,315, 5,205,093, 5,502,933, 5,613,341, and 5,720,136, the disclosures of which are incorporated herein by reference. However, none of these prior art systems has provided the combination of a stairway that is easy to manufacture, structurally sound, and visually pleasing. In particular, none of the above-referenced stairways is believed to present a stairway that looks as if made using conventional construction techniques, particularly well-suited to a furniture-quality finished, exposed wood stairway. The stairway and method of the present invention do all of this, requiring minimal skill and only a screwdriver and drill to install a stairway that meets the needs of most building applications.
In the preferred embodiment, the stringers are interlocked prior to placement in the final structure to form a strong, properly aligned frame. The frame is placed in the desired position for the stairway, and anchored. Each step module is a pre-defined unit including a tread, riser and supporting block. An initial step module is anchored to the bottom of the stringers and to the floor supporting the stairway. Subsequent step modules simply are placed on the tops of the stringers, slid into place, bearing against the preceding module, and anchored with a few screws to the stringers and preceding module. The modules may include newel posts and balusters that interlock with predefined handrail components to define a railing. The modules also may include specially designed grooves that allow the attachment of carpet to the stairway in a very clean, efficient and attractive manner. Many of these aspects of the invention may have application to stairways using conventional notched stringers.
The advantages of the present invention will be understood more readily after a consideration of the drawings and the Detailed Description of the Preferred Embodiment.